Oct 21, 2005 (CIDRAP News)  The Centers for Disease Control and Prevention (CDC), which recently reconstructed the 1918 pandemic influenza virus for research purposes, has classified the virus as a "select agent," imposing special rules on groups that handle it.

The designation means scientists and laboratories that want to work with the virus must register with the CDC and ensure that they can handle the virus safely and in accord with government guidelines, the CDC said.

"We've learned why this virus was so deadly and we know it's easily transmitted from person to person," CDC Director Julie Gerberding said in a news release. "But there is a lot we don't know so it's only logical that we take immediate steps to regulate this virus as a select agent as an added way to protect the public."

The 1918 pandemic killed as many as 100 million people worldwide. In recent years scientists succeeded in recovering fragments of the 1918 virus from the frozen body of a victim in Alaska and from preserved tissue samples from a US soldier who died in the pandemic. Those materials were used to sequence the virus's genome.

Using molecular biology techniques, CDC scientists subsequently reconstructed the virus. Two weeks ago they reported that the reassembled virus was highly lethal to mice and that it grew explosively in lab cultures of human lung cells.

Disease experts fear that the H5N1 avian flu virus now endemic in parts of Asia and moving into Europe may trigger a human flu pandemic that could echo the 1918 event. The CDC said the 1918 virus was reconstructed to help public health officials prepare for the threat of a new pandemic, to learn what made the virus so harmful, and to help develop better flu drugs and vaccines.

The virus now is one of 42 agents and toxins classified as select agents under the Bioterrorism Act of 2002, the CDC said. Other select agents include the pathogens that cause smallpox, Ebola fever, anthrax, plague, and tularemia, as well as botulinum toxin.

The CDC published the select agent classification in yesterday's Federal Register. Under the rule, parties that possess, use, or transfer the virus or its eight key gene segments must register with the CDC. "People, labs, and other facilities that work with select agents are required to ensure that they can safely handle the virus as outlined in the CDC/NIH Biosafety in Microbiological and Biomedical Laboratories, 5th edition," the CDC said.

"In addition, they are required to increase safeguards and security measures for the virus, including controlling access, screening personnel, and maintaining records to be included in a national database with records from others registered."

The designation means background checks on people working with the virus will be required, CDC spokesman Tom Skinner told CIDRAP News.

The CDC statement did not specify which of the four formal levels of biological security (biosafety, or BSL) will be required for labs handling the virus, but Skinner called it "3-plus." He said, "It was worked on here at CDC at 3-plus, which meant that all the BSL-3 level conditions were met and also enhanced measures were taken in regard to air filtration as well as the fact that the laboratorians were required to shower out before leaving the lab space."

A group of scientists appointed from several federal agencies had unanimously recommended designation of the 1918 virus as a select agent, the CDC said.